Types of Resistors by Function

There are many different types of resistors with various composition, characteristics, and functions. Some resistors are used as light sensors, while others are used to measure heat. Today, EPCB will go over four different types of resistors classified by the functions they perform. 

Power Wirewound Resistors: They can handle a large amount of power, usually up to 50W, so they are largely used in high-power applications than other resistors which only can handle a power from 0.25W to 2W. 

Precision Resistors: They have a tolerance level as low as 0.005% which means they only vary 0.005% from its nominal value. Every resistor has its own tolerance value, and that value can tell us how close to the nominal value a resistance can vary. For example, a 100Ω resistor that has a tolerance value of 10%, may have a resistance that is somewhere between 10% above 100Ω (110Ω) or 10% below 100Ω (90Ω). Because precision resistors vary very little from their nominal values, so they are largely used in ultraprecise applications.

Fusible Resistors: A fusible resistor is a wire-wound resistor used to burn open easily when the power rating of the resistor is exceeded. In a sense, a fusible resistor serves dual functions. When the power is normal, it serves as a resistor limiting current. While when the power rating is exceeded, it functions as a fuse, burning up, and become an open in the circuit to protect components in the circuit from excess current. 

Cement Resistors: They are of heat and flame resistant which is designed to handle a large amount of power flowing through it without being damaged by heat or flames. Typical power ratings range from 1W to 20W or more, and tolerances from the stated resistance value are around 5 percent.

Types of Resistors by Composition

There are many different types of resistors with various composition, characteristics, and functions. Some resistors are composed of carbon, while others are composed of metal-film. We’ll go over three main types of resistors based on their composition: carbon-composition resistors, carbon-film resistors, and metal-film resistors. 

Carbon-Composition Resistors: Carbon-composition resistors are resistors that are made of finely divided carbon mixed with a powdered insulating material as a binder in the proportions need for the desired R value. More carbon means less resistance, while more binder means more resistance. Carbon-composition resistors often are cylindrical with a brown body. The resistance values of carbon-composition resistors are commonly vary from 1Ω to 20MΩ, and the power rating is generally 0.1W, 0.125W, 0.25W, 0.5W, 1W, or 2W.

Carbon-Film Resistors: A carbon-film resistor is a resistor in which a thin film of carbon is deposited onto an insulated substrate and then cut into a spiral body. More carbon means less resistance, while more insulating material means more resistance. Carbon-film resistors have the following advantages: lower and tighter tolerances, less sensitivity to temperature changes and aging, and less noise generated internally.

Metal-Film Resistors: A metal-film resistor is a resistor in which a thin film of metal is sprayed onto a ceramic substrate and then cut into a spiral body. Unlike the above two resistors, the resistance value of a metal-film resistors are complicated which is determined by the length, thickness, and width of the metal spiral simultaneously. Compared three resistors, metal-film resistors perform the best, while carbon-composition resistors the last. 

Audio Taper Potentiometers

Audio taper potentiometers are specifically designed for audio applications. Audio taper potentiometers are used to control volume in audio devices, including headphones, headsets, computer speakers, or any volume-altering devices.

Audio taper potentiometers are log tapers, meaning any turn in the wiper of the potentiometer changes the resistance logarithmically. And that is an ideal way, because logarithmic change in resistance is more suitable for ours ears to perceive sound. 

Compared to audio taper potentiometers, use a linear potentiometer for volume control to increase or decrease sound may less accurate, because the volume changes may not turn out right as a linear taper's adjustment grows too rapidly as a pot is turned up from zero. This means that the volume levels shoot up too high when you beginning turning it up, so it is very difficult to control volume. However, log tapers are perfect for audio applications. Its characteristics are suitable to the way our ears receive increasing or decreasing sounds. It gradually increases sound as the wiper is turned. That’s why audio taper potentiometers are so widely used in audio applications.

Potentiometer

A potentiometer is a useful device used to represent a wide range of resistance. Just simply adjusting it, we can know a wide range of resistances in a circuit from anywhere near 0Ω to the specified resistance rating of the potentiometer. For instance, a 5KΩ potentiometer can be adjusted to give the resistance range from almost 0Ω to 5KΩ by adjusting the potentiometer knob.

Potentiometers are widely used in circuits, because they can increase or decrease the gain of a signal in a circuit. That means when the resistance of the potentiometer is decreased, the gain of the signal increases; or when the resistance is increased, the gain of the signal decreases. And the function can be used in circuits to control volume levels, such as the speakers, microphones.

Potentiometer Resistance Taper

Potentiometers come with a resistance taper- either linear or log. This explains how a resistance changes in value as the wiper of the potentiometer is turned. 

Linear Tapers: Linear taper potentiometers can change resistance in a linear fashion as you turn the wiper. They are the most common type of potentiometers and are widely used in potentiometer applications.

Log Tapers: Log taper potentiometers can change resistance logarithmically as you turn the wiper. They are mainly used in audio because its characteristics are suitable to the way our ears receive increasing or decreasing sounds. It gradually increases sound as the wiper is turned. Log taper potentiometers are perfect for audio applications, but that doesn’t mean they are not suitable for other applications. 

Battery Internal Resistance

In this article, we will go over the battery internal resistance. All batteries have internal resistance to some degree because the elements it composed of are not 100% perfect conductors. Though the internal resistance may be low, always around 0.1Ω  for an AA alkaline battery, and about 1Ω  to 2Ω  for a 9-volt alkaline battery, it can cause a noticeable drop in output voltage if a low-resistance load is attached to it.

This is easily understood if you still remember how voltage division works. The larger the resistance is, the more voltage gets allocated to that component. If a component has a very large impedance, that component will get most of the voltage, which comes from the battery, and vice versa. You should know that voltage gets allocated according to impedance values, so the impedance of the output device and the battery will always be divided up between each other.

Batteries with large internal resistance show poor performance in supplying high current pulses. This is because current is decreased with higher resistance. So the higher the internal resistance, the lower the current output ability. That’s why low internal resistance batteries are much better at supplying high current pulses.

Battery Eliminator

A battery eliminator is a device providing power to an electronic circuit. It can be any number of devices, such as a direct current power supply, etc. to power an electronic device. But why we use a battery eliminator instead of using batteries? 

The reason is because it can be a substitute if you do not have batteries, or you do not have the correct type, or if all of your batteries have run out of. Being that most electronic circuits run off of direct current power, you can use any direct current power source to power the electronic device, as long as you use the voltage it needs. So if all your batteries have died or you just currently don't have the right type, you can still power the device, using any device which can provide the direct current voltage which your device needs. Battery eliminators can do this.

Another reason is that if you're designing a circuit and you're trying to figure out the right voltage needed, constantly changing and swapping out batteries can be very tedious. With a battery eliminator, you can simply change direct current voltage just by adjusting a knob, and all you have to do is to rotate a switch.

Circuit Breaker Panels

If you are not familiar with the circuit breaker panels, this article posted by EPCB may be useful for you. Nowadays, circuit breaker panels have replaced the outdated fuse panels because we are running more and more electrical products. 

Some circuit breakers can control 120-volt circuits, while others are able to control 240-volt circuitry which can be used for electric dryers, electric ranges, electric water heaters, etc. Among the different circuit breakers, a main circuit breaker, usually a 100-amp or 200-amp main breaker, is the most important one with whom the whole electrical panel is powered. 

People are used to comparing a fuse with a circuit breaker, both are helpful components. But unlike a blown fuse, a circuit breaker is better for it can be reset after it trips, which means you don’t have to replace them like you do with fuses. You’d better have circuit trips and be able to reset it before finding it completely becomes a defective circuit breaker. The circuit breakers are so useful that they are widely used to power our home.

HDI PCBs

Compare to standard rigid PCB, HDI PCBs or high density interconnect PCBs require a much higher wiring and pad connection density. They are featured by finer trace and spacing, smaller capture pads, and micro-sized vias.

HDI PCBs are widely used for cell phone, tablet computer, digital camera, GPS and other different area. That’s because the market demand for lightweight and thinner PCBs which can handle high-speed signals with reduced signal loss has steadily increased, and compared to other PCBs, HDI can meet these requirements better.

Except the advantages of lightweight and steady high-speed signal, HDI PCBs also have the strengths in the following aspects. They are lower cost, better reliability, enhanced wiring density, improved design efficiency and thermal properties, advanced packaging technology, better electrical performance and signal correctness, improved frequency interference radio, electromagnetic interference and electrostatic discharge.

Advantages of Metal Core PCB

Metal core PCBs have been used frequently in electronic products, especially for LED products. In this article, EPCB would like to outline its advantages. 

Thermal Conductivity: For many double-sided PCBs or multilayer PCBs with high density and power, heat dissipation is really a big challenge, because high temperature can make electronic components fail to work. The normal PCB raw material we used frequently now, such as FR-4, has poor thermal conductivity and inter-layer insulation. So we need to use metal core PCB instead, which has an excellent thermal conductivity. 

Thermal Expansibility: There is a physical principle says objects will expand with heat and contract with cold. The CTE or coefficient of thermal expansion is different with different objects. Metal core PCB can effectively deal with the heat and the problems of thermal expansion and contraction, improve the durability and reliability of equipment.

Scale Stable: Compare with FR-4 PCB, the scale of metal core PCB is much more stable. For example, aluminum PCB is heated from 30℃ to 140~150℃, but its scale only changes from 2.5%~3%. So the metal PCB is more suitable to work in the condition of high temperature.